Mine ventilation measurements with tracer gas method and evaluations of turbulent diffusion coeffIcient

Tracer gas measurements have been carried out at the Pongkor underground gold mine, Indonesia, to evaluate mine ventilation flows and to investigate the effective turbulent diffusion coefficients in mine airways. The airflow routes and quantity, and the diffusion coefficient have been obtained by matching the measurements with numerical simulations using the advection-diffusion equation. Two leakages with flow quantity of 26.7 and 36.7 m³/s were detected. Reduction of leakages have been measured with the method after stopping the leakage routes. The turbulent diffusion coefficients for the simple airways have good agreement with the Taylor equation. However, for complex airways in operating mines, the coefficients show higher values (1.5 to 32 times) than that obtained by the Taylor equation and these have been compared with the data measured in the Kushiro coal mine, Japan. It is mainly affected by the ratio of airway length over equivalent diameter and airway frictions, but airflow mixing along the airway also has an effect on the diffusion coefficient.